In an earlier proposal shown in U.S. Pat. No. 3,933,392, issued on Jan. 20, 1976 to William Neil Wells, later abandoned in favor of copending continuation application Ser. No. 550,281, now U.S. Pat. No. 3,933,392 it was shown how the safety of a wheel and tire assembly may be enhanced by removably obstructing a well of a rim, lying between bead seats at the edges of the rim, so that it is not available to the beads of the tire mounted on the rim. The obstructor is positively held against circumferential expansion. Then if the tire suddenly loses air there is no risk of the beads escaping from the rim, something which can cause disastrous loss of control.
In co-pending application No. 537,706 (now abandoned) also assigned to the original assignee of the present application and in co-pending Canadian Pat. No. 990,327, also assigned to assignee of the present application, there was disclosed a specific form of obstructor suitable for use when the wheel rim is formed of steel. This is usually done by a pressing process. Because it is not practicable to machine a seating ledge for a band-like obstructor at the mouth of a well of such a rim, that patent shows, in its broadest aspect, how an obstructor can be positioned relative to a well of a steel rim by surfaces projecting radially inwardly to abut against a radially inward surface of the well. Specifically, for a band-like obstructor the surfaces were provided by lugs inturned from lateral edges of the band, to be face to face against side walls of the well.